Keel bone fractures affect the majority of laying hens in cage-free systems and cause chronic pain. Addressing this emerging welfare crisis requires better housing design and genetic selection.
Keel bone fractures represent a significant and growing welfare problem in cage-free egg production. The transition from conventional cages to cage-free aviary systems was welfare-positive overall by allowing natural behaviors including perching and wing-flapping. However, the three-dimensional environment of aviaries creates collision risks that cause fractures to the sternal keel. Hens with fractures show measurable pain indicators and altered behavior. The welfare irony is that the housing improvement intended to help hens has introduced a new chronic welfare problem. Solutions being investigated include aviary design modifications that reduce collision risks, genetic selection for fracture-resistant bone structure, and dietary interventions supporting bone health.